Project Abstract Approximately 34% of all fractures occur in the small bones of the wrists, hands and feet, amounting to more than 1 million annually. Considering functional losses associated with the locations of these injuries, proper reduction and fixation is critical to ensure optimal rehabilitation and recovery. Complex injuries that include irreducible fractures or segmental bone loss require operative fixation. If improperly treated, these can lead to deformities, soft tissue damage, chronic pain, and functional loss. LaunchPad Medical is an early-stage medical device company that was established to commercialize a novel bone adhesive, called Tetranite?, that is based on a synthetic, tetracalcium phosphate based biomaterial. The material is injectable, self-setting, and adhesive both to bone and metal surfaces with load-bearing strength. Over time, the material is bioresorbale and gradually replaced with new bone without losing structural strength or volume. Current orthopedic bone cements lack the combination of such properties and, for that reason, surgeons today rely on implantable fixation devices typically composed of metal in the form of plates, screws, wires, and intramedullary nails. Despite specific design efforts to reduce the size of these devices for use in small bones, many still cause adjacent tissue damage (i.e., tendon and nerve), and can sometimes result in adhesions and scarring, requiring revision surgeries. Furthermore, a single fracture often requires several of these devices to meet the needs of the fracture geometry without limiting mobility and function, leading to high procedural costs. In addition to direct costs, the nature of these injuries can result in indirect costs from temporary or permanent disability and loss of productivity. The economic burden of hand and foot fractures in the US is estimated to be $5B and $806M annually, respectively. Though physicians have explored alternative options including various forms of bone cements for fracture fixation, current materials fall short of the necessary mechanical strength to stabilize bone and lack sufficient adhesion at the bone-implant interface to serve as reliable fixation devices. Consequently, there remains a need and commercial opportunity for a minimally invasive, load-bearing, bioresorbale, and versatile adhesive solution that can meet the anatomical, mechanical, and regenerative requirements for small bone fracture reduction and internal fixation. The aim of the Phase I STTR project is to characterize the formation and structural property relationship of this self-setting bone adhesive biomaterial. The funds gained from this STTR grant will be used to (1) optimize the adhesive properties of Tetranite to meet the clinically relevant mechanical requirements for small bone fixation, (2) verify the mechanical properties and test the phase evolution of Tetranite compositions after incubation in a simulated physiological environment. The learnings from this grant will help the company move the optimal formulation into translational animal studies for small fragment fracture fixation.